Circuit interrupters



Aug. 18, 1959 s. A. BOTTONARI 2,900,477

CIRCUIT INTERRUPTERS Filed Sept. 2l, 1956 3 Sheets-Sheet l ATTORNEY Fig.l.

Aug. 18, 1959 s. A. BoTToNARl CIRCUIT INTERRUPTERS 3 Sheets-Sheet 2 Filed Sept. 2l, 1956 Fig.3`.

f f l l l 5 i l L46 n l Fig.2.

Aug- 18, 1959 l s. A. BoTToNARl 2,900,477

CIRCUIT INTERRUPTERS Filed Sept. 2l 1956 3 Sheets-Sheet 3 United States Patent O CIRCUIT INTERRUPTERS Samuel A. Bottonari, Donora, Pa., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 21, 1956, Serial No. 611,183

2 Claims. (Cl. 200-147) invention relates to circuit interrupters of the magnetic air-break type, and more particularly to magnetic air-break circuit interrupters which move an estab lished are within an adjacently dis-posed arc chute. The invention has particular applicability to magnetic air circuit interrupters utilizing a plurality of slotted plate portions spaced relatively closely together to restrict the eS- tablished arc to thereby effect its extinction.

A general object of the invention is to improve the operating performance of such types of circuit interrupters by providing induction means for drawing atmosherzic air into one or more places spaced along the length of the arc chute.

lA more specilc object of the present invention is to provide one or more aspirator ducts, or vents, leading into the arcing space from the region externally of the arc chute, thereby to enable fresh, clean, un-ionized air to be .sucked into the arcing space by inductive action.

:Still a Afurther object of the invention is to provide an improved magnetic air-break circuit interrupter of the multiple slotted plate type with one or more modified plate sections, so that one or more aspirator ducts may be provided to result in a supplementary, or an auxiliary ow of cool, fresh, un-ionized air into the arcing space within the arc chute from the region externally of the arc chute.

The present invention is particularly concerned with airbreak magnetic circuit interrupters, particularly those adaptable for high-voltage application. However, the present invention has certain aspects, which may be applied to the lower voltage circuit interrupters. The dielectric recovery of an arc chute depends upon the rate of ydielectric recovery of the arc space, and any method that can introduce a clean atmosphere of gas, such as air, without additional auxiliaries would augment the dielectric reeOvery of the interrupter. Moreover, the concept employed in the present invention may additionally be used to improve existing designs, which may further increase their interrupting eiciency and capacity.

During the period of arc extinction, considerable energy is released just before, and at the instant of, arc extinction in the vicinity of the slot apex of each ceramic plate in spaced, slotted plate types of interrupters. lt is kan object of the present invention to introduce at one or more places along the length of the arc chute a supplementary fiow of cool, fresh and un-ionized gas to assist the arc chute in performing its arc-extinguishing funcden.

Still afurther object of the present invention is to in- `lpflllce one or more plate sections at certain intervals along the length of the stack constituting the arc chute, such plate sections having vented portions of such configuration as to provide one or more aspirator ducts, which will enable clean, fresh air to be sucked into the arcing space from the region externally of the arc chute.

Still a further object of the present invention is to improve'the operation of magnetic air-break circuit interrupters by reducing the time provided for interruption,

'2,900,477 Patented Aug. 18, 1959 ICC and thereby reduce the amount of energy released within the arc chute during an interrupting operation.

Although certain features of the invention are illustrated in connection with an arc chute of the type constructed from a stack of separate, spaced slotted plate portions cemented together, it is to be clearly understood that the invention could readily be applied to the interleaving fin type of arc chute, in which certain plate portions within the arc chute are attached, or integrally formed, with one side arc chute wall, whereas the complementary plate portions may be attached to, or formed as an integral part of, the complementary or opposing arc chute side wall. Thus, some of the advantages of my invention may be readily obtained by using either the stacked construction or the interleaving 1in construction, there being no essential difference between the two as far as obtaining the benefits of certain aspects of the present invention.

Additional objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

Figure 1 is a side elevational View, partially in vertical section, of an air-break magnetic type circuit interrupter embodying the principles of the invention, and the contact structure being illustrated in the closed-circuit position;

Fig. 2 is a fragmentary vertical sectional view taken substantially along the line lI-II of Fig. l;

Fig. 3 is an enlarged sectional view through one of the Vented ceramic plates utilized in the construction of Figs. 1 and 2;

Fig. 4 is an enlarged view of one of the slotted plates utilized in the stacked arc chute of Figs. l and 2;

Fig. 5 is an enlarged sectional view taken through another type of plate which may be used in a variation of the construction of Figs. l and 2; and

Figs. 6 and 7 illustrate plate sections which may be futilized in a modified type of stacked arc chute provided with opposite pairs of aspirator ducts leading into the arcing space from opposite sides of the arc chute.

Referring to the drawings, and more particularly to Fig. l thereof, the reference numeral 1 generally designates suitable contact structure, which, when separated to the open circuit position, establishes an arc which is moved upwardly into the entrance portion of a generally rectangularly-shaped arc chute, designated by the reference numeral 2, as a result of the transverse magnetic field set up by the blowout coil 3 and associated magnet structure 4. A rotatable contact arm 5 carries a conducting bridge 6 which, in the closed circuit position, as shown in Fig. l, interconnects stationary main contacts A contact stud 9 carries the current from the stationary main contact 7, through an insulating bushing l0 to the external circuit. The contact stud for the. statlonary main contact 8 is not shown, but it may be identical to the contact stud 9.

Consequently, in the closed circuit position of the interrupter, as shown in Fig. l, the electrical circuit comprises the Contact stud 9, stationary main contact 7, conducting bridge 6, stationary main Contact 8, to the Contact stud therefor, not shown, to the external circuit.

During the opening operation of the interrupter, the Contact arm 5 is rotated in a clockwise direction about a pivot pin, not shown, but which is in electrical contact `with the stationary main contact S to draw an are between the arcing contacts ll, l2 after the separation of conducting bridge 6 from the main contacts 7, 8.

When the arcing contacts 1l, l2 separate, the are formed therebetween will expand `upwardly because of theloop circuit so that one terminal thereof will be transferred to the arc terminal member 18, and the other 3 arc terminal will be transferred to the other are terminal member 19.

When this occurs, the blowout coil 3 will be put into series circuit, and the transverse magnetic field set up thereby between the field pole members or side magnetic pole plates 14 (Fig. 2) will move the established aro upwardly along the arc terminal members 1S, 19 into the generally rectanmilarly-shaped arc chtite 2. The electrical circuit now comprises contact stud 9, conductor 20, blowout coil 3, contact clip 15, arc terminal member 18, the arc itself, arc terminal member 19, flexible shunt Z8, contact arm to the other contact stud, not shown.

' The arc chute 2 comprises an insulating rectangularlyshaped housing member 22 positioned adjacent to an insulating plate 21, the latter serving as a base for the blowout coil 3. Within the housing 22 is placed a plate 24 composed of an insulating material. Two insulating spacer strips 2S space a plate 26, composed of an insulating material, away from the plate 24. The plate 26 may have a plurality of apertures 27 formed therein, which facilitate the venting of arc gases therethrough, particularly when high currents are to be interrupted. Two more insulating spacer strips 25 space the plate 26 from a plurality of elongated slotted plates 29, 30, forming a unitary plate assembly. The plates 29, 30 are composed preferably of a refractory insulating material, such as a Zircon porcelain, `which does not give off gas when contacing an arc. The plates 29, 30 are respectively illustrated, in enlarged manner by Figs. 4 and 3 of the drawings.

Above the arc terminal member 19 is a second insulating plate 26, which is spaced by spacer strips 25 from the right-hand plate 29 of the plate assembly. Two additional spacer strips 25 space the right-hand plate 26 from a refractory plate, not shown, which is, in turn, separated from the right-hand end of the housing 22 by a plurality of strips of iish paper. Bolts 33a secure the several strips 25, plate 26 and the housing 22 to the plate 21. Bolts 34a secure the right-hand plate 26 and its spacer strips 2S and fish paper strips to the housing 22.

The plates 29, 30 and asbestos rope strips 35 may be cemented together in a preliminary process to form a unitary plate assembly, which may be bodily placed into the rectangular housing 22. Insulating holding strips 39 are secured by bolts 38 to the opposed inner sides of the housing 22 to prevent the unitary assembly of plates 29, 30 from being forced upwardly out of the exhaust end of the housing 22 by the pressure of gas formed during the interrupting operation.

Referring to Fig. 4, which more clearly shows the conguration of each insulating plate 29, it will be observed that each elongated plate 29 has an inwardly extending slot or notch 46, which constricts in lateral dimension in a direction toward the top of the plate 29. The closed end of the slot 4i) forms an apex, which is designated by the reference numeral 41.

Fig. 3 more clearly shows the construction of the ceramic plate 30. It will be observed that again a slot or notch 41B is provided having a closed apex 41, but, in addition, the plate portion 30 has embossed raised portions 42, 43, and 44, on its surface which not only space the plate 31B away from a contiguously disposed plate 29, as indicated in Fig. 1, but also provide an aspirator vent, or duct, indicated by the reference numeral 45. The inner end of the aspirator duct, it will be noted, with reference to Fig. 3, leads to the region adjacent the closed apex 41, for a purpose to be described hereinafter. It will be obvious that the edges of the slots 40 of the plates 29, 30 collectively dene a tapered are passage which becomes more constricted in a direction toward the exhaust end of the arc chute 2.

Preferably, the apices 41 are staggered alternately throughout the arc chute 2 so that when the arc is forced upwardly into the several slots 40, it will assume a zigzag configuration at the upper closed ends 41 of the slots 40 prior to its being extinguished.

The interleaving of the plates 29, 30 results in the apices 41 being staggered throughout the length of the arc chute, so that an apex 41 is first to one side of the center line 46 of the plate and then to the other side of the center line 46 of the adjacent plate.

By way of recapitulation, with reference to Fig. l, it will be observed that beginning at the left-hand end of the arc chute 2, first a plate 29 is employed, which is followed by a plate 30, which is in turn followed by a second plate 29. Between the plate 30 and the second plate 29 are the asbestos rope spacers 35. Then follows a second plate 30, etc. It will thus be seen that the closed ends of the several slots 41 will be alternated throughout the length of the arc chute. If it is desired to vary the plate arrangement so that a vented plate is needed with the closed slot end 41 thereof disposed on the opposite side of the center line 46 of the plates in a variation of the foregoing arrangement, then a vented plate 31 (Fig. 5) is utilized. Obviously, different arrangements may be used according to particular interrupting requirements.

In the particular construction shown in Fig. 1 wherein only the plates 29 and 30 are employed, it will be observed that the upper closed ends 41 of the slots are staggered about the center lines 46 of the plates. Since the arc is halted at this position, it is subjected to an un-ionized ow of gas from below the arc stream in accordance with the theory of U.S. Patent 2,442,199 issued to Robert C. Dickinson and Russell E. Frink and assigned to the assignee of the instant application.

As well known by those skilled in the art, the are stream is very hot and causes an upward flow of gas within the arcing region 47. By induction action, the aspirator ducts 45 will cause a supplementary flow of cool, fresh un-ionized air from outside the arc chamber below the side magnetic pole plates 14 to be drawn into the arc region adjacent the apices 41 through the aspirator ducts 4S as indicated by the arrows 48. A window 52 is cut through the arc chute jacket below the side magnetic pole plates 14, as shown in Fig. 1, to vent the lower ends of the aspirator ducts 45. This inductive action will assist the natural action of the arc chute in cooling and deionizing the arc stream, and will thereby decrease the interrupting time of the interrupter, with the further result of reducing the amount of energy released within the arc chute.

In a particular modied construction utilizing both plates 30 and 31 (Fig. 5) interspersed with plates 29 of the type illustrated in Fig. 4, the supplementary blast will be drawn in the arc chute 2 from both side walls thereof.

For particular applications it may be desirable to utilize in conjunction with the plates 29, which are preferably staggered as before, double injection plates of the type indicated at 50 and 51, respectively, illustrated in Figs. 6 and 7. With lreference to these figures, it will be observed that each vented plate 50, 51 has a pair of aspirator ducts 45 leading into the arcing space from opposite sides of the plate. In this case, the windows 52 need to be cut through both sides of the arc-chute jacket 22.

.From the foregoing description it will be apparent that there has been provided an improved magnetic air-break circuit interrupter in which the slot shape according to the foregoing patent is not changed, and in addition supplementary air blasts are obtained by embossed plate sections having aspirator ducts. The location of the plate sections may be varied and introduced at even, 0r alternate intervals, and in any number of combinations, each such embossed plate section forming a Venturi duct. The vented plate sections 30, 31, 50, 51 may be interspered at intervals with the regular plates 29 to form any combination of injecting ducts directed at, or adjacent the apex 41 of the slot 40.

As can be realized, there is a powerful upward ow of gases during the upward thrust of the are, and a properly placed duct will allow an independent flow of air, as illustrated in Fig. 2. The self-injection of this air, which in .itself will become a delayed flow, can be directed at the slot and in this manner should help the interrupter as follows:

(a) Cools .the ionized gases and the plate apex.

(b) Dilutes then ionization with fresh un-ionized gas.

(c) Helps to clean up any ionized or near ionized debris (arc products).

(d) May actually reduce head pressure in the ceramic stack assembly so as to, in effect, make the blowout magnet more effective.

From the foregoing description it will be apparent that the vented plate sections 30, 31, 50, 51 may be used in any manner of combination, and, if desired, the apices 41 do not need .to be off-center, but may line up with the center line 46 of thearc chute 2. The vented plate sections may provide one or two aspirator ducts, and if the arc is to be staggered by off-set apices 41, embossed plate sections, which are mirror images of each other, may be employed as illustrated in Figs. 3, 5 and 6, 7. The same advantages will reside in any combination, namely, the drawing in of auxiliary air blasts by inductive action, all brought about by the presence of the aspirator ducts 45. Not only do the embossed portions of the plate sections provide such aspirator ducts 45 but they also provide a spacing means between the plates, thereby taking the place of the asbestos rope sections 35 formerly used.

The cumulative arc-extinguishing action brought about by the slots 40 in the plates, together with the gradual restriction of such slots 40, in addition to the use of the aspirator ducts 45 all contribute to bring about rapid interruption. As mentioned, the particular location and arrangement of the aspirator ducts 45 is a matter of choice depending upon the particular rating requirements.

By splitting the several plates along the lines 55, it will be readily apparent to one skilled in the art that one portion of each plate section could be integrally formed with one side wall of the arc chute, whereas the other' portion of each plate section could be an integral part of the opposing side wall. In other words, the advantages of my invention could be readily adapted to an interleaving fin type of arc chute, as well as to the stacked construction illustrated in Figs. 1 and 2 of the drawings.

Although there have been shown and described specific embodiments of the invention, it is to be clearly understood that the same were given merely by way of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

I claim as my invention:

1. A magnetic air circuit interrupter of the type operable in atmospheric air independently of an external source of stored compressed gas including a generally rectangularly-shaped arc chute, the arc chute having opposite ends thereof open defining an entrance portion and an exhaust portion, contact means separable to establish an arc adjacent to said entrance portion of the generally rectangularly-shaped arc chute, a magnetic blowout structure including a U-shaped portion having side magnetic pole plates disposed on opposite sides of the generally rectangularly-shaped arc chute, means for setting up a transverse magnetic field between said magnetic pole plates for effecting movement of said established arc through the arc chute toward the exhaust portion thereof, said generally rectangularly-shaped arc chute including a plurality of relatively thin, insulating, non-gasevolving plate portions of at least two different types, a

first type of relatively thin insulating non-gas-evolving plate portion being elongated in the direction of arc movement and having a closed tapered elongated slot therein extending in the long direction of the elongated plate portion with the open end of the closed slot disposed at the entrance portion of the arc chute, a second type of relatively thin insulating, non-gas-evolving plate portion also being elongated in the direction of arc movement and also having a closed tapered slot therein extending in the long direction of the elongated second plate portion with the open end of the closed slot also disposed at the entrance portion of the arc chute, the side edges of the tapered closed slots in the first and second types of insulating relatively thin plate portions collectively defining a tapered arc passage within said arc chute becoming more constricted in the direction of arc movement toward the exhaust portion of the arc chute, the second plate portion in addition having embossed raised portions on its surface cooperating with a contiguously disposed rst plate portion to define one or more elongated aspirator ducts extending in the general direction of the plate slot and at only a small angle thereto, the one or more aspirator ducts leading from the sides of the arc chute to the region immediately adjacent the apices of the closed slots of the first and second plate portions and directing one or more auxiliary jets of cool atmospheric air externally of the arc chute and into the constricted end of the arc passage in the general direction of arc movement toward the exhaust portion of the arc chute, and said one or more aspirator induced jets of cool atmospheric air assisting arc interruption at said apices and deionizing remnant arc products to prevent reignition of the arc at said separable contact means.

2. A magnetic air circuit interrupter of the type operable in atmospheric air independently of an external source of stored compressed gas including a generally rectangularly-shaped arc chute, the arc chute having opposite ends thereof open defining an entrance portion and an exhaust portion, contact means separable to establish an arc adjacent to said entrance portion of the generally rectangularly-shaped arc chute, a magnetic blowout structure including a U-shaped portion having side magnetic pole plates disposed on opposite sides of the generally rectangularly-shaped arc chute, means for setting up a transverse magnetic field between said magnetic pole plates for effecting movement of said established arc through the arc chute toward the exhaust portion thereof, said generally rectangularly-shaped arc chute including a plurality of relatively thin, insulating, non-gas-evolving plate portions of vat least two different types, a first type of relatively thin insulating non-gasevolving plate portion being elongated in the direction of are movement and having a closed tapered elongated slot therein extending in the long direction of the elongated plate portion with the open end of the closed slot disposed at the entrance portion of the arc chute, a second type of relatively thin insulating non-gas-evolving plate portion also being elongated in the direction of are` movement and also having a closed tapered slot therein extending in the long direction of the elongated second plate portion with the open end of the closed slot also disposed at the entrance portion of the arc chute, the side edges of the tapered closed slots in the first and second types of insulating relatively thin plate portions collectively defining a tapered arc passage within said arc chute becoming more constricted in the direction of arc mo'vement toward the exhaust portion of the arc chute, the second plate portion in addition having embossed raised portions on ifs surface cooperating with a contiguously disposed first plate portion to define one or more elongated aspirator yducts extending in the general direction of the plate slot and at only a small angle thereto, the one or more aspirator ducts leading from the sides off the arc chute below the side magnetic pole plates to the region immediately adjacent the apices of the closed slots of the rst and second plate portions and directing one or more auxiliary jets of cool atmospheric air externally of the arc chute and into the constricted end of the arc passage in the general direction of arc movement toward the exhaust portion of the arc chute, and said one or more aspirator induced jets of cool atmospheric air assisting arc interruption at said apices and deionizing remnant arc products to prevent reignition of the arc at said separable contact means.

UNITED STATES PATENTS Hobson June 2, Beiersdorf et a1. June 9, Prince Aug. 4, Baker et al. Apr. 4, Dickinson et al. May 2S,

FOREIGN PATENTS Germany Mar. 22, 

